Various technologies exist for connecting homes and offices to communications service providers such as telephone service providers, cable television providers, and internet providers. For many years, simple copper wire was used to provide telephone service to homes and offices, and this infrastructure is still used for deploying telephone and internet services to some customers. More recently, coaxial cable has been used for communications, first to deliver television content and later to provide internet services.
Fiber optic cable is the next step in the evolution of communications technology. Fiber possesses substantial advantages over copper wire, including faster connections and higher-fidelity signals. However, fiber has not been extensively deployed directly to homes and offices, due largely to the fact that fiber has been relatively expensive. Instead, until recently, fiber has been mainly used for long-distance networks, or for “backbone” networks which connect smaller local or regional networks together.
Fiber costs have steadily declined, however, and has become a feasible alternative to coaxial cable and copper wire for delivery of telecom services directly to a home or office. Such “Fiber-to-the-premises” (FTTP) has been deployed in some areas, with service providers deploying “triple play” communications packages including telephone, television, and broadband internet access over such fiber connections.
Two competing technologies have emerged in the deployment of FTTP: “Active FTTP,” which requires powered electrical components to propagate and route signals to the proper location, and “Passive Optical Networks (PONs)” which use passive “optical splitters” to route signals to the proper location.
In the typical PON, residences or offices, i.e. subscriber buildings, are connected to the communication service provider's “central office,” which, in turn, is connected to a backbone network. In order to connect subscriber buildings to the central office, a fiber cable known as a “feeder cable” runs from the central office to the neighborhood, and is physically connected to one or more “fiber distribution hubs.”
Inside each fiber distribution hub, one or more “splitter chassis” are connected to the feeder cable. The splitter chassis contains optical splitters for routing data to and from different subscriber buildings. When a new subscription requires a building to be connected to the fiber network, one of the optical splitters is connected to a “distribution panel” to enable service to the building. The distribution panel is, in turn, connected to the building through a “distribution cable.”
In many instances, the number of fiber connections in a given area is relatively small, but the network must accommodate new fiber connections as they are added. When a housing development is built, for example, it is desirable to provide an infrastructure for delivering fiber services to homes within the development. This can be accomplished by choosing a fiber distribution hub of the appropriate size to provide service to the homes anticipated to be built in the development, and connecting the buildings in the development to the distribution panels in the fiber distribution hub as the homes are built. However, this approach can be problematic, because fiber distribution hubs can be costly.
One significant factor contributing to the up-front cost of current fiber distribution hubs is the cost of the distribution panels and the optical components therein. At present, fiber distribution hubs are assembled fully populated with distribution panels. Thus, the initial cost of a fiber distribution hub includes the cost of all the optical components installed in the distribution panels. Higher-capacity hubs have higher initial costs, largely due to the optical components in the distribution panels.
In the housing development example discussed above, if the development is built over a three year period of time, for example, not all fiber connections need to be made in the initial phase of construction. Accordingly, there is no need for a fully populated distribution hub at that time. In addition to the “wasted” capacity of a hub, optical component costs generally decline over time. Accordingly, purchasing a fiber distribution hub to meet the planned development size is generally more costly at the outset than it would be if the purchase of optical components within the hub could be delayed until a connection is actually needed. Finally, if the development is not completely finished, it is likely that a fiber distribution hub chosen to meet the planned size of the development will be too large, resulting in a sunk cost that is difficult to recover.
Therefore, it is desirable to provide a fiber distribution hub which reduces the initial cost of deploying fiber services. It is further desirable to provide expandable fiber distribution hubs, so that more subscribers can be connected to existing hubs without having to add or replace entire fiber distribution hubs.